Processing facilities and other facilities routinely include tanks for storing liquid materials and other materials. For example, storage tanks are routinely used in tank farm facilities and other storage facilities to store oil or other materials. As another example, oil tankers and other transport vessels routinely include numerous tanks storing oil or other materials.
Often times, it is necessary or desirable to measure the amount of material stored in a tank. This may be useful, for example, during loading of material into the tank or unloading of material from the tank. As particular examples, “custody transfers” and “weights and measures of oil” often require highly accurate measurements from level gauging instruments installed on the roof of a tank. In bulk storage tanks, an error of one millimeter in a level reading can correspond to several cubic meters of volumetric error. This can result in losses of thousands of dollars for one or more parties.
One approach to measuring the amount of material in a tank involves non-contact radar sensing, which is becoming more and more popular. In this approach, radar signals are transmitted towards and reflected off the surface of material in a tank. This approach typically offers more flexibility and less maintenance in various tank content measurement scenarios. However, in real-world situations, radar level gauges often cannot perform reliably due to unexpected interferences or other unstable conditions (such as power failures). Moreover, conventional radar level gauges often need to be recalibrated after a power failure.